This is old but still a valid question. Carey's answer below only needs a
bit of modification:

1. The Product Key for the 64-bit version of Windows XP
is only valid with the 64-bit version of Windows XP.
It cannot be used to install a 32-bit version of Windows XP.
If one wishes to "downgrade" to a 32-bit version, then
he'll need to purchase a "Full Version" of the 32-bit version
of Windows XP and perform a "clean install".

Note: Not exactly. No purchase is necessary for a downgrade. You can call
Microsoft licensing at 888-352-7140, give them the 64-bit key and they will
in turn give you a 32-bit key because you are downgrading. You will need the
media to complete your install.


2. The Product Key for the 32-bit version of Windows XP
is only valid with the 32-bit version of Windows XP.
It cannot be used to install a 64-bit version of Windows XP.

Note: This is true the way it is stated. Neither key is valid for the other
operating system. The correct answer is, you can “downgrade� as in number 1,
but you cannot “upgrade� from 32-bit to 64-bit by calling in.

John Thompson
Microsoft Partner

--
Carey Frisch
Microsoft MVP
Windows - Shell/User
Microsoft Community Newsgroups
news://msnews.microsoft.com

"Satyajit Roy" wrote:

> Hi,
>
> Can anyone help me to understand the exact licencing policy for MS XP Pro 64
> bit OS OEM Pack in the below scenario.
>
> 1. If the user is buying Win Xp Pro 64Bit OS OEM Pack preloaded(Factory
> installed) in the system, what will be the licencing policy for downgrading
> the same to 32Bit ? Can the customer buy media for 32 bit and load the same?
>
> 2. If the user is buying Win Xp Pro 32Bit OS OEM Pack preloaded(Factory
> installed) in the system, what will be the licencing policy for upgrading the
> same to 32Bit ? Can the customer buy media for 64 bit and load the same?
> --
> Regards,
> Satyajit

Are you able to obtain the downgrade key from Microsoft for an OEM version? .
Regards,
chris

"JOWATH" wrote:

> This is old but still a valid question. Carey's answer below only needs a
> bit of modification:
>
> 1. The Product Key for the 64-bit version of Windows XP
> is only valid with the 64-bit version of Windows XP.
> It cannot be used to install a 32-bit version of Windows XP.
> If one wishes to "downgrade" to a 32-bit version, then
> he'll need to purchase a "Full Version" of the 32-bit version
> of Windows XP and perform a "clean install".
>
> Note: Not exactly. No purchase is necessary for a downgrade. You can call
> Microsoft licensing at 888-352-7140, give them the 64-bit key and they will
> in turn give you a 32-bit key because you are downgrading. You will need the
> media to complete your install.
>
>
> 2. The Product Key for the 32-bit version of Windows XP
> is only valid with the 32-bit version of Windows XP.
> It cannot be used to install a 64-bit version of Windows XP.
>
> Note: This is true the way it is stated. Neither key is valid for the other
> operating system. The correct answer is, you can “downgrade� as in number 1,
> but you cannot “upgrade� from 32-bit to 64-bit by calling in.
>
> John Thompson
> Microsoft Partner
>
> --
> Carey Frisch
> Microsoft MVP
> Windows - Shell/User
> Microsoft Community Newsgroups
> news://msnews.microsoft.com
>
> "Satyajit Roy" wrote:
>
> > Hi,
> >
> > Can anyone help me to understand the exact licencing policy for MS XP Pro 64
> > bit OS OEM Pack in the below scenario.
> >
> > 1. If the user is buying Win Xp Pro 64Bit OS OEM Pack preloaded(Factory
> > installed) in the system, what will be the licencing policy for downgrading
> > the same to 32Bit ? Can the customer buy media for 32 bit and load the same?
> >
> > 2. If the user is buying Win Xp Pro 32Bit OS OEM Pack preloaded(Factory
> > installed) in the system, what will be the licencing policy for upgrading the
> > same to 32Bit ? Can the customer buy media for 64 bit and load the same?
> > --
> > Regards,
> > Satyajit